The present invention relates to expandable intraluminal prostheses for use in body passages, and more particularly, to self-expanding intraluminal prostheses useful for the treatment of body passages, such as blood vessels, occluded by disease.
Self-expanding prostheses are commonly used to restore and maintain the patency of body passages, particularly blood vessels. Self-expanding prostheses include stents constructed from shape memory materials, such as Nitinol, stents constructed of conventional materials, such as stainless steel, in a configuration that exhibits self expansion characteristics, and other varieties of prostheses. Such self-expanding stents can be compressed into a reduced diameter state suitable for percutaneous insertion into the body passage through a catheter. The self-expanding stent is typically held in the reduced diameter state until delivery into the body passage, whereupon the self-expanding stent is released to an increased diameter state within the body passage to hold open the body passage.
Problems associated with such conventional self-expanding stents include the need for pre-dilation of the body vessel, typically with a catheter-deployed balloon, prior to deployment of the self-expanding stent. Pre-dilation of the body vessel is necessary because the self-expanding stent alone frequently lacks sufficient radial expansion strength to completely open the diseased body vessel. Additionally, post-dilation of the self-expanding stent can be necessary to ensure the self-expanding stent has deployed to a sufficient diameter to engage the walls of the blood vessel. The need for pre- and post-dilation increases the duration of the medical procedure and the risk to the patient.
Additionally, conventional self-expanding stents generally require a separate containment system, for example a delivery tube or sheath, that radially constrains the stent in the reduced diameter state during catheter delivery and until the stent is deployed within the body vessel. Frequently, the self-expanding stent moves within the body vessel as the containment system is removed, adversely effecting the accuracy of the deployment of the stent within the body vessel. Moreover, the removal of the delivery sheath once the stent is in place requires an additional step, prolonging the medical procedure and, thus, the risk to the patient.